Boom angle and alarm indicator



March 1, 1966 A J. c. MlNoGUE 3,238,521

BOOM ANGLE AND ALARM INDICATOR Filed sept. e, 196s INVENTOR Ip, JOHN c. MINOGUE United States Patent O 3,238,521 BOOM ANGLE AND ALARM INDICATOR John C. Minogue, 85 Perry Ave., Staten Island, N.Y. Filed Sept. 6, 1963, Ser. No. 307,115 Claims. (QI. 340-267) This invent-ion relates' to a device for remotely visually indie-ating the angle of a crane boom and the like to` a reference and of indicating audibly and/or visually when predetermined boom angles are reached.

In the operation of boom rigged equipment such as a crane, it is often necessary not to exceed certain boom angles in order to avoid capsizing the crane or in order to avoid striking surrounding structures. Also, when the crane is being used to locate a load with accuracy, it is usually necessary for the boom to be relocated in a predetermined angular position cach time the load is deposited. While the crane operator with or without the help of additional personnel may attempt visually to assume that the boom does not exceed a certain angle or is repositioned at a certain angle, the accuracy of such visual observation leaves much to be desired. Also, at times it is inconvenient, if not quite difficult, for the crane operator to observe the boom angle.

Accordingly, it is the object of this invention to pro vide a novel and improved device adapted to be located in a remote loc-ation, such as the cab of a crane, which will permit the crane operator at all times to be aware of lthe relative elevation of the boom.

It is a further object of this invention to provide such a device which will assist the operator in relocating the boom repeatedly in the same position with a high degree of accuracy; included within this object is the further object of providing novel and improved adjustable means -for determining the boom angle or angles at which the device will be actuated, with said adjustable means being freely accessible to the crane operator without requiring any disassembly of the device.

It is still a further object of this invention to provide a device of the type described which is simple and economical in constnuction, yet is rugged and dependable to assure l-ong and reliable service.

Other objects will be in part obvious, and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a front view of a boom angle indicator constructed in accordance with this invention;

FIG. 2 is a cross-sectional view substantially along the line 2 2 of FIG. l; and

FIG. 3 is a wiring diagram for the electrical components o-f the device of FIG. l.

With reference to the drawings, the boom angle indicator of this invention comprises `a generally rectangular cast metal housing or frame having a rear wall 11, side walls 12 and 13, a bottom wall 14, and top wall 15. FPhe bottom wall 14 is provided with a boss 16 having a bore by means of which the indicator may be easily mounted in a vertical position on a cylindrical support. The rear wall 11 is provided with a central boss 18 having an opening in which is ixedly engaged one end of a reel shaft 20. A cable reel 22 is rotatably mounted on the shaft 20. More particularly, the reel 22 is provided with a `hub'24 having a bore within which is received a cylindrical bearing 26 seated at one end ofthe boss 18, The bearing is provided at its end nearest the ice rear wall 11 with an annular lip or flange which is seated in a counterbore in the bore of the hub 24 to provide means for spacing `the reel properly from the rear wall 11.

Extending from the hub 24 in a radial direction is the circular, disc-like body 28 of the 4reel which lies parallel to the rear wall 11 of the housing. The body 28 is provided adjacent its periphery with an annular cable supporting portion or drum 30 which is disposed concentrically of the axis of the shaft 20 and extends toward the rear wall 11. A cable 32 is in vpart wound about the drum 30 with one end being suitably connected to the drum. Trhe other end portion of the cable extends outwardly of the housing through an opening in the bottom wall 14. The drum 30 is spaced pe-ripherally of the reel body 28 to provide a shoulder which prevents run off of the cable at 4one end of the drum. At its other end, adjacent the rear wall 11, the drum is provided with an upstanding lip or flange extending radially outwardly of the drum to prevent the cable Ifrom running off the end of the drum. In order to assure that the cable will be in a single layer on the drum, a generally cylindrical cable retainer 34 is disposed concentrically about the drum 30 and is spaced radially outwardly of the drum an amount just slightly more than the thickness of .the cable. The retainer `is formed from a strip of exible resilient material, such as spring steel. The ends of the retainers are rolled over to provide semi-cylindrical hook portions which are engaged over cylindrical yposts or dowels 36. The dowels are mounted on the rear wall 11 and extend parallel to the axis of the drum 30. The dowels are located on opposite sides of and relatively close to the point of tangency that the cable makes with the cable drum. To assemble the retainer, the ends of the retainer are merely engaged over `the dowels 36, whereby the retainer will assume its generally cylindrical shape and `will be held on the dowels by the resilience of the material from which the retainer is fabricated.

In order to provide for retraction of the cable 32, a coil spring 38 is provided. The spring is disposed over the boss 18 on the rear wall with the inner end of lthe spring being suitably iixed to the boss. A spring retainer is provided by a cylindrical extension 40 or the reel body 28. The retainer 40 is disposed concentrically of the shaft 20 and is disposed between the boss 18 and cable drum 38. The outer end portion 41 of the spring 38 extends through a slot (not shown) -in the retainer 4() and by the engagement with the bordering edge portion of the slot provides driving engagement between the spring and reel 22. As the cable is drawn oit the reel, the spring 38 will be ten-sioned thereby 'providing a bias on the cable to prevent slackness and assuring that when the force is removed from lthe cable, the reel will be rotated in a reverse direction to again wind the cable onto the reel.

The reel is maintained on the shaft 20 by an acorn nut 42 mounted on the threaded outer end of the shaft.

A Washer is disposed between the nut 42 and a disc-like dial plate 44 which is mounted on the hub 24 of the reel 22. More specifically, the dial plate has a central opening fitting over the Ibearing 26 which extends beyond hub 24 to provide a shouldered seat for the dial plate. Screw 46 serves to x the dial plate to the hub 24 of the reel 22. The dial plate carries a dial 48 on which may be provided numeric indicia as well as graduations between the indicia. As can be seen from FIG. 1, the dial is visible in its entirety from the front of the device.

A xed reference pointer 50 cooperates with the dial 48 to provide a visual indication of the amount of dial rotation from its zero position. The pointer is 3 mounted on a front panel 52 which is secured at its corners to the housing 10. The panel has a circular cut out or opening of a diameter just slightly less than that of the dial plate 44. Mounted on the front panel 52 are a pair 4of lamp assemblies 54, 55 for providing illumination of the dial. Also mounted on the front panel is an indicator light assembly 56 which will become illuminated when the boom to which the cable 32 is connected is positioned in one of a plurality of angular positions to provide a visual indication to the operator that a critic-al boom angle has been reached. The lamp 56 is controlled by a normally open micro-switch 58 which is carried by a bracket depending from the top wall 15 of the housing. The switch has an actuating arm or lever carrying at its outer end a cam roller which is engageable by a plurality of cam pointers 62 carried by the dial plate to actuate the switch and etiect energizing of the lamp 56. As best shown in FIG. 2, each cam pointer has a slot or groove permitting the cam to be fitted over the dial plate. On the reverse side of the dial plate, the plate is provided with a circular groove in which is engaged the reduced cylindrical end portion of a set screw 66 carried by the cam. The set screw serves to retain the cam on the dial plate and 'by selective threading of the set screw into the groove a preselected frictional resistance to movement of the cam along the dial plate may be provided. In order to securely lock the cams in adjusted position about the dial plate periphery, each cam carries a socket head screw 68, which is engageable with the front face of the dial plate to clamp the cam to the dial plate and outwardly beyond the front panel 52 where it is readily accessible for adjustment of cam position.

As will be seen from FIG. 1, each cam 62 serves as a pointer by reason of the generally triangular configuration of the portion thereof located forwardly of the dial plate and exposed within the circular opening in the front panel. Also it will 'be observed that the top of each cam is provided with a pair of sloping or inclined side portions 74, 75 to facilitate engagement with the cam roller 60 and prevent damage to the switch Iby reducing the shock loading of the roller on initial engagement thereof by a cam.

In order to provide an audible as well as visual indication of the boom reaching a critical or desired angle, an electrically energized bell 76 is mounted on the top wall l of the housing. Also mounted on the top wall is a push button switch 78 for testing the electrical circuit and a toggle switch Si) for controllin the dial illuminating lamps 54, 55. The electrical circuit for the boom angle indicator of this invention is shown in FIG. 3.

The circuit is designed Afor simplicity of installation in that it requires only a single wire connection to a power source with the return path lbeing provided through the housing to the crane frame. More particularly, the positive lead is connected to one side of the normally open switch 5S which is connected in series through the indicator light S6 and bell 76 to ground in the housing 10. The test switch 78 is connected in parallel across the switch S8. The illuminating lamps 54, 54 are connected in parallel and between the grounded housing 1t) and :one side of the lamp control switch St). The other side .of the switch 80 is connected to the power source.

In use, the boom yangle indicator is mounted on a crane, preferably in the cab adjacent the operator and in a location where the indicator is readily and conveniently viewed. The free end of the cable 32 is fixed to a convenient location -on the boom. The cable is played from the boom through a series of pulley and guide blocks back to the indicator in a suitable manner whereby the dial will be rotated as the boom is pivoted in a vertical plane. In the embodiment shown the dial graduations are of equal spacing consistent with a linear relation of dial rotation to boom movement. However, this relationship will most likely not exist. Thus the dial indication will not throughout movement of the 'boom between a horizontal and a vertical position accurately indicate the angle of the boom to t-he horizontal. However, the dial will indicate relative position and, if desired, a nonlinear scale could be provided for any given installation to permit exact boom angle readings. Any inaccuracies in exact angle measurement of the `boom is not considered serious in that a primary advantage of the present device is to permit the operator to re-spot the lboom in a predetermined location. In other words, the cams 62 are set at preselected positions angularly about the dial, which positions correspond to predetermined `boom limit or spotting locations. Once the cams have been set, whenever the boom reaches a predetermined angle, the operator will be made visually and audibly aware of the situation. Thus, the operator may prevent the location of the boom at dangerous angles and may accurately position the 'boom `for blind unloading or loading of material. A particular advantage of the present invention is the manner and ease of which the cams may be relocated. Due to the construction of the housing and the arrangement of the cams and their mounting, the cams are freely accessible from the rfront of the device so that they may be quickly and accurately repositioned as desired.

Inasmuch as many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall `be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim:

1. In a boom angle indicator, a housing, a resiliently biased cable drum rotatably supported on the housing, a dial plate mounted for rotation with said drum, a cam adjustably mounted on said dial plate for rotation therewith and for selective movement relative to said plate about the axis thereof, switch means cooperable with said cam to provide actuation of the switch means in response to movement of the dial plate with a predetermined angular portion about its axis, said dial plate being circular, said cam having a groove receiving a peripheral edge portion of the dial plate, a threaded member extending at right angles to and carried by said cam and directly engageable with the front of the dial plate to clamp the cam in selective adjusted position on the dial plate, said housing being provided with a front wall having an opening through which said dial is viewed, said opening having a bordering edge portion which is disposed outwardly of said threaded member, whereby said threaded member is accessible through said opening for adjustment of said cam, said dial plate having an annular groove on the rear face thereof disposed concentrically of the dial plate axis, and a second threaded member carried by said cam and engageable within said annular groove to provide frictional resistance to movement of the cam about the axis of the dial plate and to retain the cam on the dial plate when the first mentioned threaded member has been threaded out of engagement with the dial plate.

2. In a boom angle indicator, a housing having a rear wall, a pair of side walls and a top and bottom wall, a shaft xed to said rear wall and extending at right angles thereto and forwardly thereof, a cable reel rotatably supported on said shaft, a spring biasing said cable reel in one direction of rotation, said reel-being provided with a cylindrical portion, a flexible cable wound about said cylindrical portion in a single layer with one end of the cable being fixed to the reel and the other end of the cable extending outwardly of said housing, cable retainer means separate from and mounted on said housing and including a generally cylindrical member disposed coaxially of said cylindrical portion and spaced from the cable supporting surface of said cylindrical portion a distance substantially no greater than the diameter of said cable, a dial plate mounted for movement with said cable reel, a plurality of cams carried by the dial plate adjacent the periphery thereof, switch means supported on the housing and actuatable by said cams, indicating means controlled by said switch means, said housing being provided With a front panel disposed in parallel spaced relation to said rear wall and overlying said dial plate, said front panel having an opening through which said dial plate is viewed, and means mounting the cams on the dial plate for selective adjustment thereof in a plurality of positions about the dial plate axis including releasable means securing the cams in selective adjusted position on the dial plate, said releasable means being disposed at least in part within the bordering edge portion of said opening in the front panel so as to be accessible through said opening for adjustment of said cams.

3. A boom angle indicator as described in claim 2 in which said dial plate is in the shape of a circular disc, each of said cams having a groove receiving an edge portion of the dial plate, said releasable means comprising a threaded member carried by each cam engageable with the front of the dial plate to clamp the cam in selected position on the dial plate.

4. A boom angle indicator as described in claim 3 in which said dial plate has an annular groove on the rear face thereof disposed concentrically of the dial plate axis, and a second threaded member carried by each of said cams and engageable Within said annular groove to provide frictional resistance to movement of the cam about the axis of the dial plate and to retain the cam on the dial plate when the rst mentioned threaded member has been threaded out of engagement with said dial plate.

5. A boom angle indicator as described in claim 2 in which said cable retainer means comprises an elongated strip of flexible resilient material, the ends of said strip being provided with hook-like portions, a pair of xed supports disposed on opposite sides of and relatively close to the point of tangency of said cable as it leaves said reel, said hook-like portions being engaged over said supports and being retained thereon by the resilience of the material from which said strip is fabricated.

References Cited by the Examiner UNITED STATES PATENTS 1,966,958 7/1934 Fisher 20G-38.1 2,050,555 8/1936 Bickley 20G-38.1 2,288,636 7/1942 Malone 20C-38.1 2,346,066 4/1944 Conrad 340-267 2,941,496 6/1960 Leischer 116-114 3,011,261 12/1961 Riley 340-267 NEIL C. READ, Primary Examiner.

LOUIS I. CAPOZI, Examiner. 

1. IN A BOOM ANGLE INDICATOR, A HOUSING, A RESILIENTLY BIASED CABLE DRUM ROTATABLY SUPPORTED ON THE HOUSING, A DIAL PLATE MOUNTED FOR ROTATION WITH SAID DRUM, A CAM ADJUSTABLE MOUNTED ON SAID DIAL PLATE FOR ROTATION THEREWITH AND FOR SELECTIVE MOVEMENT RELATIVE TO SAID PLATE ABOUT THE AXIS THEREOF, SWITCH MEANS COOPERABLE WITH SAID CAM TO PROVIDE ACTUATION OF THE SWITCH MEANS IN RESPONSE TO MOVEMENT OF THE DIAL PLATE WITH A PREDETERMINED ANGULAR PORTION ABOUT ITS AXIS, SAID DIAL PLATE BEING CIRCULAR, SAID CAM HAVING A GROOVE RECEIVING A PERIPHERAL EDGE PORTION OF THE DIAL PLATE, A THREADED MEMBER EXTENDING AT RIGHT ANGLE TO AND CARRIED BY SAID CAM AND DIRECTLY ENGAGEABLE WITH THE FRONT OF THE DIAL PLATE TO CLAMP THE CAM IN SELECTIVE ADJUSTED POSITION ON THE DIAL PLATE, SAID HOUSING BEING PROVIDED WITH A FRONT WALL HAVING AN OPENING THROUGH WHICH SAID DIAL IS VIEWED, SAID OPENING HAVING A BORDERING EDGE PORTION WHICH IS DISPOSED OUTWARDLY OF SAID THREADED MEMBER, WHEREBY SAID THREADED MEMBER IS ACCESSIBLE THROUGH SAID OPENING FOR ADJUSTMENT OF SAID CAM, SAID DIAL PLATE HAVING AN ANNULAR GROOVE ON THE REAR FACE THEREOF DISPOSED CONCENTRICALLY OF THE DIAL PLATE AXIS, AND A SECOND THREADED MEMBER CARRIED BY SAID CAM AND ENGAGEABLE WITHIN SAID ANNULAR GROOVE TO PROVIDE FRICTIONAL RESISTANCE TO MOVEMENT OF THE CAM ABOUT THE AXIS OF THE DIAL PLATE AND TO RETAIN THE CAM ON THE DIAL PLATE WHEN THE FIRST MENTIONED THREADED MEMBER HAS BEEN THREADED OUT OF ENGAGEMENT WITH THE DIAL PLATE. 